Fix McbpConnection::getPrintableKey()
Fix McbpConnection::getPrintableKey()

For some reason the buffer did not get zero terminated
(at least on debian8) so it would print out some random
characters at the end..

Change-Id: I3bcb237ca78e17ee4d8f2b601f2080a3d5c640e2
Reviewed-on: http://review.couchbase.org/75539
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Jim Walker <1cd02e31b43620d7c664e038ca42a060d61727b9@couchbase.com>

daverigby/kv_engine,couchbase/memcached,daverigby/kv_engine,daverigby/memcached,daverigby/kv_engine,couchbase/memcached,daverigby/memcached,daverigby/kv_engine,daverigby/memcached,couchbase/memcached,couchbase/memcached,daverigby/memcached